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In the movie, 1917, there is huge crater filled with muddy water and bodies, what could have caused it? It is a bit too big for an artillery shell.

Yu Zhang
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6 Answers6

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That all depends on how big the artillery shell was.

selection of artillery shells

A standard 75mm/18lb shell would have difficulty making a hole anywhere near that big, but the largest shell fired in WWI was 3,130 lbs! used by the 520mm French Schneider Howitzer...

enter image description here

Somewhat more portable were the 24cm or 25cm Schwerer Flügelminenwerfer* which carried a 200 lb charge…
*Roughly translates to 'heavy winged mine thrower' - the shells had fins at the rear.

enter image description here

Then there was Big Bertha - with a 17" barrel - which could leave shell craters as wide as 9 m (29 ft 6 in) and as deep as 6 m (19 ft 8 in).

enter image description here

It's quite difficult to picture the size of this - it was 15ft tall, 32ft long

Kilian Foth
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Tetsujin
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    The cannon in the 3rd picture could be upcycled as a telescope. My 10inch dobsonian looks almost exactly the same. :D – Eric Duminil Jan 19 '20 at 13:22
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    Difficult to tell from only the one frame shown, but the crater shown looks consistent with the described effect of Big Bertha. – Anthony X Jan 19 '20 at 23:49
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    for the 3rd one (Big Bertha), wikipedia fr has an image with people around: https://fr.wikipedia.org/wiki/Grosse_Bertha#/media/Fichier:Dicke_Bertha.Big_Bertha.jpg – Olivier Dulac Jan 20 '20 at 13:11
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    To help with the scale in the third picture, look at the ladders at the front and imagine an artilleryman scrambling up one. – Oscar Bravo Jan 21 '20 at 09:55
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    "Roughly translates to 'heavy winged mine thrower'" - Ah, German is such a beautiful language. – Michael W. Jan 21 '20 at 18:44
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Possibly the result of an underground bomb, placed there by miners:

One of the common techniques used in warfare during the First World War was mining. There were various mines planted under trenches, then detonated to send part of the trench, and anyone in it, sky high.

The BBC also did an article on this.

National Geographic says of the Messine explosion(s):

This Explosion Was the Biggest Blast Before Atomic Bombs

[...]

The mines were each fired by soldiers and so went off a few seconds apart up and down the length of the ridge, sending geysers of earth, steel, concrete, and bodies spewing into the air and searing the dark sky with orange flame.

The mines, totaling nearly 1 million pounds of explosives, are believed to have created one of the largest human-caused explosions before the nuclear era. On the British side of the front, men were knocked off their feet by the blast. Farther away, in France, the shockwave was mistaken for an earthquake. And the roar of the detonation was reportedly so tremendous that it was even heard by the British Prime Minister in London.

The craters resulting from the Battle of Messines are fairly well-known:

BCdotWEB
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  • "send part of the trench, and anyone in it, sky high." that's a weird idea. Surely the main effect would be a subsidy? The technique has been used for centuries, both for breaching walls and coal mining (both with and without explosives). – Luaan Jan 21 '20 at 07:45
  • @Luaan https://www.nationalgeographic.com/news/2017/06/biggest-blast-before-atomic-bombs-messines-world-war/ "On June 7, 1917, British forces detonated 19 massive mines beneath German trenches, blasting tons of soil, steel, and bodies into the sky." – BCdotWEB Jan 21 '20 at 14:47
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    The largest was Spanbroekmolen. 41 tonnes of high explosive were detonated. It left a crater 75metres in diameter and 21metres deep – CSM Jan 21 '20 at 19:57
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Given all you see is the crater, there's no guarantee it was made by a single shell, though the odds are statistically high it was a shell given how many were fired.

The biggest crater created still exists today in 2020, 104 years after it was created.

The crater is 30 metres deep and 100 metres across (98 feet and 330 feet) and was caused by a 2,700 kilogram (6000 lb) high explosive charge triggered on 1916-07-01 at 07:28.

The Lochnagar mine crater on the 1916 Somme battlefields in France is the largest man-made mine crater created in the First World War on the Western Front. It was laid by the British Army's 179th Tunnelling Company Royal Engineers underneath a German strongpoint called “Schwaben Höhe”.

Further info http://www.greatwar.co.uk/somme/memorial-lochnagar-crater.htm and https://en.wikipedia.org/wiki/Lochnagar_mine

Another thought - there's no reason it couldn't be a series of shells, each landing in the previous crater. Estimates range from 1.7 billion to 8 billion rounds fired by both sides, and that France has a land area of 643,801 km², of which very roughly 25% was directly in a warzone at some point. Meaning 10,000 to 40,000 rounds landed on each square kilometre on average, with many more in heavily contested areas.

(This last part is super-fudgy with estimates, don't take it accurately at all.)

Criggie
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    Multiple shell hits would result in a non-circular crater as each successive shells would land on slightly different points - while the Royal Artillery (and, I imagine, the German equivalent) prides itself on precision in delivery, the exact trajectory of the shell is subject to multiple factors including wind (and gusts), the manufacturing tolerance of each shell and the charge to propel it, the temperature of the gun breach and barrel (they get hotter with successive rapid firings), and even the temperature of the charge before loading. – HorusKol Jan 19 '20 at 13:10
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    @HorusKol true - it would be very hard to put two shells on exactly the same spot. Though the odds of any shell landing somewhere that another has already detonated is not zero either. Realistically this question's proper answer is handwave "movie magic" – Criggie Jan 20 '20 at 02:23
  • I honestly can't believe the needed the accuracy on the propellant tolerance alone, but I'll give you one @HorusKol missed: Recoil moving the gun. Even WW2 radar assist bombers didn't get the needed accuracy, you'd need to wait for bombers with more advanced guided munition. – Kaithar Jan 21 '20 at 00:42
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    @Kaithar of course that would be very hard to do on purpose, but drop enough shells on an area and eventually one will land in a previous shell hole. At the Somme, "the British artillery fired more than 1.5 million shells during the preliminary bombardment, more than in the first year of the war." It would be statistically very unlikely for no shell to land where another already had. – Criggie Jan 21 '20 at 01:18
  • @Kaithar I don't know the exact numbers, but I do know that stored charge temperature is regularly taken and entered into the range computers used to generate bearing/elevation for fire missions – HorusKol Jan 21 '20 at 02:10
  • @Criggie Absolutely so, the catch is the probability of hitting the same spot without ruining the nice circular crater. Makes a horrible probability. – Kaithar Jan 23 '20 at 12:19
  • @HorusKol that's neat... I'm not sure recall can be gauged though, you'd need to compensate based on the surface type and the mechanical properties of the mount. Any given shot will move the gun's mount and aim, you'd either need to fix the positioning after each shot or compensate with the aim. Not impossible with modern tech but the old mechanical range computers? – Kaithar Jan 23 '20 at 12:28
  • @Kaithar this is getting into a lengthy discussion. Returning the gun to the same firing position would have been trivial with many WWI guns - especially the wheeled variety. They'd be on tracks that slope such as recoil would push them back up the slope. Gravity would then pull them back to a stop which ensured the gun was fitting from the exact same position. – HorusKol Jan 23 '20 at 13:11
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    @Kaithar even modern artillery used simple ways to account for recoil and return - we just anchored our guns to a big plate on which the wheels sat. 20 years ago, I had a spotter (the guy who directs fire) buy me a pint after landing all 10 rounds in a rapid fire mission on the same (decommissioned) target tank one time - and I couldn't even see the tank directly. Apparently it was quite spectacular. The Brits put a lot of work on indirect artillery support around the start of the 20th Century, and have kept refining it since then. – HorusKol Jan 23 '20 at 13:19
  • @HorusKol in most case, that would definitely help, we could say it's repeatable aiming to within a couple of degrees, so it would be a question of target range and some trig to figure out if the margin of error is significant. Definitely a lot easier with modern artillery. An interesting problem, but yeah, definitely getting lengthy. – Kaithar Jan 23 '20 at 13:21
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In addition to the incredibly heavy shells that could be lofted by the artillery of either side, delayed fuzes were used which trigger a few seconds after impact, causing the shell to explode under the surface, pushing the ground around the impact up and out, creating craters as deep and wide as you see in the picture you posted.

While air burst shrapnel shells were around, they relied on timers being set to a precision such that they would explode at the right height for maximum effect. Proximity fuzes, which would allow reliable airbursts, were not in use until the Second World War, so the sub-surface explosion was the preferred devastating and effective anti-infantry tactic. It had the added advantage of turning no-man's land into a crater riddled quagmire, making it that much harder for an attacking force to progress.

HorusKol
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    I'm probably just showing my ignorance here, but where you say Since proximity fuzes, which would allow airbursts and are very effective in throwing shrapnel out, were not in use until the Second World War - the shrapnel airburst shell was a 19th century invention and was much improved and in use by all sides in WWI - am I missing something here? – Spratty Jan 20 '20 at 12:11
  • @Spratty: Airburst is effective against infantry in the open, but even a mediocre shelter would protect you from shrapnel, and shrapnel does little against barbed wire obstacles. Delayed fuse was fired against enemy bunkers, and most importantly, into no-man's land to destroy the barbed wire (so infantry could follow up with a charge, without getting held up by the wire and mowed down by machine guns. Or so was the theory.) – DevSolar Jan 20 '20 at 15:57
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    @Spratty before the proximity fuze, shrapnel shells relied on a timed fuze - which needed to be set before loading, relying on the judgement of the loader or gun commander to set the correct time, and carried significant risk of premature detonation. They were still used early in the war to some degree but, by the middle of the war, high-explosive shells were being manufactured in cases that fragmented into shrapnel - but most of these would have been impact detonated rather than airburst. – HorusKol Jan 20 '20 at 23:34
  • @HorusKol - I wasn't doubting your (quite correct) statement that the proximity fuze (I will never get used to that spelling) was a WWII phenomenon, just that it was only the proximity fuze that permitted air-burst shrapnel shells. I recently watched a documentary (I think it was "WWI In Colour" but can't be sure as I've deleted it now) which had footage of ABSS in use and interviews with front-line troops about their effects and what it was like to be above ground when they started arriving - absolutely horrific. Anyway, I obviously missed the word "reliable" - we're agreed on that one. – Spratty Jan 21 '20 at 10:56
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It is a bit too big for an artillery shell.

Others have shown the artillery pieces, and the mine craters.

But few people today have any idea of how much the heavy artillery of the day churned up the landscape in general. The earth was pounded over and over for months, which means that eventually it was just a thick layer of mud (which got displaced even easier with each successive barrage).

Borrowing from the "heaviest shell" link in Tetsujin's answer, emphasis mine:

In March 1918 for every mile of their 50-mile trench network, the German Army had 92 field guns. In addition to [those] 92 field guns [...], they had 31 field howitzers, 14 medium howitzers, 14 heavy guns, 7 heavy howitzers and 3.5 super heavy howitzers for each mile of trench.

Respecting the photographer's copyright, I just link to some pages showing the fields of carnage, almost a hundred years later -- with some of the craters still in evidence rivaling that from your question:

Quiet on the Battle-scarred fields (blogspot.com)

100 years on, buried WWI shells pose threat in French fields (reuters.com) (which is -- part of -- the reason why these areas have not been taken under the plow again. Also, chemicals, and body parts of the many thousands that were blown into so small pieces that burial was simply not an option.)

Verdun battlefield scars (YouTube)

DevSolar
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The script refers to it as a 'mine crater'.

Large shell holes appear on either side of them. They pick their way through them, balancing carefully along the ridges. They climb to the top of a small hillock and suddenly on the other-side - VERTIGO.
The ground falls away steeply in a mine crater, stories DEEP.
They look down into it.

It's not clear if they mean 'a crater caused by an underground munition' or 'a crater caused by a team of miners placing an explosive under the enemy'. Given the depth and size it could equally be either.

Valorum
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